Evaluation of Image Quality Using the Normalized-Rank Approach for Primary Class Liquid-Crystal Display (LCD) Monitors with Different Colors and Resolution

Abstract

The purposes of this study were to evaluate the image quality of five types of liquid-crystal display (LCD) monitors by utilizing the normalized-rank approach and to investigate the effect of LCD monitor specifications, such as display colors, luminance, and resolution, on the evaluators' ranking. The LCD monitors used in this study were 2, 3 and 5 mega-pixel monochrome LCD monitors, and 2 and 3 mega-pixel color LCD monitors (Eizo Nanao Corporation). All LCD monitors were calibrated to the grayscale standard display function (GSDF) with different maximum luminance (recommended luminance) settings. Also, four kinds of radiographs were used for observer study based on the normalized-rank approach: three adult chest radiographs, three pediatric chest radiographs, three ankle joint radiographs, and four double-contrasted upper gastrointestinal radiographs. Ten radiological technologists participated in the observer study. Monochrome LCD monitors exhibited superior ranking with statistically significant differences (p<0.05) compared to color LCD monitors in all kinds of radiographs. The major difference between monochrome and color monitors was luminance. Therefore, it is considered that the luminance of LCD monitors affects observers' evaluations based on image quality. Moreover, in the case of radiographs that include high frequency image components, the monitor resolution also affects the evaluation. In clinical practice, it is necessary to optimize the luminance and choose appropriate LCD monitors for diagnostic images.

Technical and radiological image quality comparison of different liquid crystal displays for radiology

“…We established some technical differences, but like Samei et al, we could not find any statistically significant differences in radiological assessments made with different LCDs 5. This was consistent with most reported studies, where no diagnostic differences were found between LCDs with different specifications 5,6,8,9–12,14–16…”

“…Deterioration of the color filters in color LCDs might lead to rapid decreases in luminance 8. Kuroki et al suggested that the luminance of LCDs affected observer evaluations 6. Second, our radiological assessments were based on AAPM TG-18 criteria, but we did not investigate specific diagnostic criteria.…”

“…However, the standard deviations are completely overlying. Several studies have found that the technical specifications and performance can vary among different monitor types (LCD, CRT) and also among hard-copy radiograph films; nevertheless, very few differences have been reported in their accuracy for clinical evaluation 2,3,6,8,11–14. In the present study, although slight technical and radiological differences were noted, the evaluated medical grade diagnostic 3-MP and 6-MP LCDs showed comparable image quality when calibrated accurately.…”

“…Several studies have compared imaging monitors with different specifications, like cathode ray tubes (CRTs) versus LCDs,2–5 diagnostic versus office grade or clinical review grade monitors,6,7 and monochrome versus color monitors 6,8–10. Also, comparisons have been made between monitors that varied in number of pixels and pixel size 11–16.…”

“…However, the use of office-grade monitors for diagnosis has been discouraged, despite some studies that demonstrated acceptable quality 6,7. In most studies, no significant differences were found between color and monochrome monitors 8,9,10,18.…”